In the present state of the art certain potentiometers are known, which in some cases have a housing in which they ore located and retained by means of a plange which provides the fixing of the unit to its corresponding support or base by means of a pin having a threaded portion at its outer surface, while inside of said pin slides a shaft, which is attached to the pointer and through the activation thereof, allows for the desired adjustments of said potentiometer. These potentiometers, use the process of bending the ends of terminals over the coinciding ends of resistive plate in order to provide contact between said terminals, whereby in order to obtain the desired contact a considerable pressure is to be exerted thereupon. The collector of the potentiometers to which reference is being made, incorporate at a central point thereof a cylindrical shape provided for guiding the end of the pointer carrier, said cylindrical shape being formed by means of bending and pressing the material towards outside. In other cases, said cylindrical shape is obtained simply by a punching action. Further, to be mentioned as a constructive element in the known potentiometers is the flanging of the pointer carrier over the collector thus allowing for the sliding and guiding of said pointer carrier.
The aforementioned potentiometers have the problem of not having a uniform and reliable rigidity or absence of movement between the potentiometer as such and the housing in which it is located, because the perimetral flanging for fixation requires a highly controlled pressure, in order to avoid, in some cases, deformation of the element, and in others, to provide an ostensible clearance. Iqually to the previous case, the flanging of the pointer carrier turns out to be somewhat troublesome because if the pressure applied is not sufficient, clearances would be formed, whereas if said pressure is too strong, an excessive friction with the cylindrical shaped collector which would cause difficulty in the sensibility of the adjustment of the rotor and the pointer over the resistive track. Also, obstruction in the rotation of the pointer carrier may be caused by the presently existing operations for drilling the collector as in the case of bending, the point of stretching may suffer breakage which obviously dampers a regular sliding of the pointer carrier, whereas in the case said drilled portion is punched, rough edges are logically produced which undisreably damper the uniform rotation of the pointer carrier.
Another problem which the present potentiometers have is that if the control shaft is damaged, it cannot be substituted and the complete potentiometer would be thrown away.
The bending or nipping which presently is practiced for transmitting the electric energy by contact between the resistive track and the associated terminals thereof presents the drawback of producing intermittent losses of electric continuity because the system used for bending the lug permits a logical recovery of the material which tends to loosen off from the opposing contact surface. In the case of attempting to avoid the aforementioned loosening off by applying a higher constant force in the bending, one faces the risk of obtaining excessive deformations which damage the element.